Question

I am working with a webservice which gives me an image as an array of integers. I have managed to convert this array into an NSData object and then into a UIImage using the code below.
Now I am in doubt how I will convert an image into a similar array.

The array looks like this:

[255,216,255,224,0,16,74,70,73,70,0,1,1,1,0,96,0,96,0,0,255,219,0,67,0,8,6,6,7,6,5,8,7,7,7,9,9,8,10,12,...]

This is the code I use to convert the above array to a UIImage.

+ (UIImage *)imageFromBytes:(NSArray *)bytes
{
    unsigned char *buffer = (unsigned char *) malloc(bytes.count);
    int i = 0;
    for (NSDecimalNumber *num in bytes)
        buffer[i++] = num.intValue;
    NSData *data = [NSData dataWithBytes:buffer length:bytes.count];
    free(buffer);

    return [UIImage imageWithData:data];
}

So, I need to convert a UIImage into an array of integers (a byte array).

Can anybody point me in the right direction?

Answer 1

You can get the data for an image with:

UIImage *image = [UIImage imageNamed:@"image.png"];
NSData *data = UIImagePNGRepresentation(image);

If you use a JPG you can use UIImageJPEGRepresentation.

And then, extract the array of bytes:

NSUInteger len = [data length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [data bytes], len);
free(byteData)

You can use also the method (void)getBytes:(void *)buffer length:(NSUInteger)length from NSData:

[data getBytes:&byteData length:len];